001/* 002 * Portions of this software was developed by employees of the National Institute 003 * of Standards and Technology (NIST), an agency of the Federal Government and is 004 * being made available as a public service. Pursuant to title 17 United States 005 * Code Section 105, works of NIST employees are not subject to copyright 006 * protection in the United States. This software may be subject to foreign 007 * copyright. Permission in the United States and in foreign countries, to the 008 * extent that NIST may hold copyright, to use, copy, modify, create derivative 009 * works, and distribute this software and its documentation without fee is hereby 010 * granted on a non-exclusive basis, provided that this notice and disclaimer 011 * of warranty appears in all copies. 012 * 013 * THE SOFTWARE IS PROVIDED 'AS IS' WITHOUT ANY WARRANTY OF ANY KIND, EITHER 014 * EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY 015 * THAT THE SOFTWARE WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF 016 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND FREEDOM FROM 017 * INFRINGEMENT, AND ANY WARRANTY THAT THE DOCUMENTATION WILL CONFORM TO THE 018 * SOFTWARE, OR ANY WARRANTY THAT THE SOFTWARE WILL BE ERROR FREE. IN NO EVENT 019 * SHALL NIST BE LIABLE FOR ANY DAMAGES, INCLUDING, BUT NOT LIMITED TO, DIRECT, 020 * INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES, ARISING OUT OF, RESULTING FROM, 021 * OR IN ANY WAY CONNECTED WITH THIS SOFTWARE, WHETHER OR NOT BASED UPON WARRANTY, 022 * CONTRACT, TORT, OR OTHERWISE, WHETHER OR NOT INJURY WAS SUSTAINED BY PERSONS OR 023 * PROPERTY OR OTHERWISE, AND WHETHER OR NOT LOSS WAS SUSTAINED FROM, OR AROSE OUT 024 * OF THE RESULTS OF, OR USE OF, THE SOFTWARE OR SERVICES PROVIDED HEREUNDER. 025 */ 026 027package gov.nist.secauto.metaschema.core.util; 028 029import java.util.Objects; 030import java.util.stream.Stream; 031 032import edu.umd.cs.findbugs.annotations.NonNull; 033 034public final class ObjectUtils { 035 private ObjectUtils() { 036 // disable construction 037 } 038 039 /** 040 * Assert that the provided object is not {@code null}. 041 * <p> 042 * This method sets the expectation that the provided object is not {@code null} 043 * in cases where a non-null value is required. 044 * 045 * @param <T> 046 * the object type 047 * @param obj 048 * the object 049 * @return the object 050 */ 051 @NonNull 052 public static <T> T notNull(T obj) { 053 assert obj != null; 054 return obj; 055 } 056 057 /** 058 * Require a non-null value. 059 * 060 * @param <T> 061 * the type of the reference 062 * @param obj 063 * the object reference to check for nullity 064 * @return {@code obj} if not {@code null} 065 * @throws NullPointerException 066 * if {@code obj} is {@code null} 067 */ 068 @NonNull 069 public static <T> T requireNonNull(T obj) { 070 if (obj == null) { 071 throw new NullPointerException(); // NOPMD 072 } 073 return obj; 074 } 075 076 /** 077 * Require a non-null value. 078 * 079 * @param <T> 080 * the type of the reference 081 * @param obj 082 * the object reference to check for nullity 083 * @param message 084 * detail message to be used in the event that a {@code 085 * NullPointerException} is thrown 086 * @return {@code obj} if not {@code null} 087 * @throws NullPointerException 088 * if {@code obj} is {@code null} 089 */ 090 @NonNull 091 public static <T> T requireNonNull(T obj, @NonNull String message) { 092 if (obj == null) { 093 throw new NullPointerException(message); // NOPMD 094 } 095 return obj; 096 } 097 098 /** 099 * A filter used to remove null items from a stream. 100 * 101 * @param <T> 102 * the item type 103 * @param item 104 * the item to filter 105 * @return the item as a steam or an empty stream if the item is {@code null} 106 */ 107 @SuppressWarnings("null") 108 @NonNull 109 public static <T> Stream<T> filterNull(T item) { 110 return Objects.nonNull(item) ? Stream.of(item) : Stream.empty(); 111 } 112 113 @SuppressWarnings("unchecked") 114 @NonNull 115 public static <T> T asType(@NonNull Object obj) { 116 return (T) obj; 117 } 118 119 @SuppressWarnings("unchecked") 120 public static <T> T asNullableType(Object obj) { 121 return (T) obj; 122 } 123}